The present invention generally relates to mechanism for an optical disc driver, and more particularly to a tilt angle adjusting mechanism for adjusting a tilt angle of an optical axis of the pickup head relative to the optical disc.
The drivers for optical disc become more and more popular, and even indispensable in the current information industry. For example, drivers for reading CD-ROM or DVD ROM has now been well matured.
Please refer to FIGS. 1A and 1B which are the front and side views of a general optical disc driver. The optical disc driver includes a spindle motor 10, an optical pickup head 30 and a mecha chassis 20. The spindle motor 10 is fixed on an unshown motor base which is further fixed to the well-planed mecha chassis 20. An objective lens 31 is positioned on the optical pickup head 30 which is movably mounted on two guide rods 40a and 40b. The guide rods 40a, 40b are fixed to the mecha chassis 20 via holders 50a, 50b. The paralleling and positioning of the guide rods 40a, 40b are determined by the precision and positioning of the holders 50a, 50b and the mecha chassis 20.
The spindle motor 10 in the optical disc driver has to be precisely positioned in order to keep the data bearing surface of the optical disc, e.g., CD or DVD, perpendicular to the optical axis of the objective lens 31 in the optical pickup head 30, so that the information data can be correctly read. Generally, the tilt angle of the spindle motor 10 relative to the optical pickup head 30 or the guide rods 40a, 40b has to be well adjusted for the right positioning. The conventional tilt angle adjusting mechanisms can be classified into two kinds:
1) by adjusting the spindle motor 10. In this manner, the adjusting mechanism which piles on the spindle motor will occupy a certain space, easily pierce holes on the circuit board, increase the complexity of mechanical design, increase the difficulty of adjustment, and restrain a compact design of the optical disc driver;
2) by adjusting the guide rods 40a, 40b. This manner will cause the transmission mechanism of the optical pickup head 30 fail when the pickup head is driven via a gear-rack transmission.
The present invention provides a tilt angle adjusting mechanism for adjusting a tilt angle of an optical axis of a pickup head relative to the optical disc. The mechanism can easily adjust the guide rods to well position the optical axis of the pickup head so that the data stored on the optical disc can be correctly read by a laser beam.
In an optical disc driver having a spindle motor fixed on a chassis for carrying an optical disc to be read, and an optical pickup head including a laser beam for reading data from the optical disc, the tilt angle adjusting mechanism according to the present invention, for adjusting the optical axis of the pickup head perpendicular to the plane of the optical disc, includes:
a first and a second guide rods, parallel to each other, for carrying the optical pickup head, each of which includes a rotation prevention end and an adjusting end;
an adjusting element, connected to the adjusting end of the guide rod, for generating an axial movement along the axis of the guide rod; and
a fixed holder and an adjusting holder for supporting the guide rod. The holders are fixed on the mecha chassis for respectively supporting the two ends of the guide rod. The adjusting holder receives the adjusting element for adjusting the guide rod moving toward or away from the optical disc. The fixed holder is furnished with a slot for tightly receiving the rotation prevention end of the guide rod so as to pre vent the rod from rotation during adjustment.
A pressing element for providing a pressure to tightly fix the adjusting element to the adjusting holder.
The mecha chassis can be defined as an X-Y plane with an X axis where the guide rods extend, and a Y axis perpendicular to the X axis. When adjusting the tilt angle of the optical axis of the pickup head, we may first adjust the adjusting element of the second guide rod to move the second guide rod toward or away from the optical disc, so as to rotate the optical axis on the X axis based on the first guide rod. Or, we may adjust both adjusting elements of the first and second guide rods to move the adjusting ends of the rods and make the rods rotate on the Y axis. By adjusting the aforesaid X or Y axis rotation, a suitable tilt angle can be attained.